So i'm planning to build this bike up using Ultegra R8020 but i'm not sure what bottom bracket i would need. When I purchased the frame I was given these "cups" but im not sure if this is a good alternative solution. The bearings that are preinstalled have Enduro 6806 ABEC-3 written on them.
It's a BB30 frame with a normal BB30 bottom bracket in it. The adapters you picture are 24mm spindle adapters that plug in and reduce the ID to the 24mm that Shimano cranks want, and put the face to face spacing where they expect.
The other way to do it is use one of the press-in threaded inserts like the FSA one, into which you can then install a threaded bottom bracket, or use a thread-together adapter BB.
Since you already have these that's probably reason enough to do it that way. They're simple and work but have the drawbacks that they maintain the longevity and creak issues BB30 can have.
The 24mm BB30 adapters I usually use completely take the place of the BB30 bearing shields that the BB comes with. I can't tell if yours do or not, so you'll need to see what fits best and seems to provide correct spacing for the cranks.
Many BB30 frames have internal routing schemes that render the plug-in adapters the only practical choice due to access or interference considerations.